In the communications field, to exchange a message, every device needs to send a signal. A signal is a tool for carrying a message, is a carrier of a message, and is a physical quantity or a pulse (such as a voltage, a current, or magnetic field strength) that can be perceived. Information or a message can be transmitted by using the signal.
People want to experience more and require a signal transmission speed to be as high as possible. Theoretically, provided that a medium carrying and transmitting a signal is increasingly wide, more signals are transmitted in one-off transmission, and therefore the speed is increasingly high. However, because of physical reasons such as a level and because people can only process a limited pulse fluctuation frequency in the prior art, in the current cable field, a frequency division multiplexing technology is basically used to separate a downlink frequency band and an uplink frequency band that are used to transmit a signal. For example, in a previous Data Over Cable Service Interface Specifications (DOCSIS) 3.0 standard, a U.S.-standard definition is uplink signal (US): 5 MHz to 42 MHz and downlink signal (DS): 57 MHz to 1002 MHz, and a European-standard definition is US: 5 MHz to 65 MHz and DS: 87 MHz to 1002 MHz. In the current latest DOCSIS 3.1 technology, uplink and downlink spectra are re-divided: US: 5 MHz to 204 MHz and DS: 258 MHz to 1200 MHz. A pulse fluctuation frequency that can be processed cannot be easily changed. Therefore, how to properly and flexibly split an uplink signal and a downlink signal becomes another manner for resolving the problem by people.
In the prior art, one device only supports one frequency mixing specification, for example, 42 MHz/55 MHz. If a frequency band needs to be re-divided subsequently, the original frequency mixing specification needs to be replaced by a new frequency mixing specification on the device site, for example, 65 MHz/87 MHz, or 87 MHz/108 MHz, or 204 MHz/258 MHz. In this way, a signal frequency band needs to be changed by means of manual setting, which is not intelligent, is not flexible, and consumes plenty of resources.